From: Christoph Hellwig Subject: Re: [RFC][PATCH 7/9]ext4: Add the EXT4_IOC_FIEMAP_INO ioctl Date: Fri, 31 Oct 2008 06:05:47 -0400 Message-ID: <20081031100547.GA22093@infradead.org> References: <49019EF6.4000706@rs.jp.nec.com> <20081026084048.GF3184@webber.adilger.int> <20081026084848.GA9270@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Akira Fujita , linux-ext4@vger.kernel.org, Theodore Tso , Mingming Cao To: Andreas Dilger Return-path: Received: from bombadil.infradead.org ([18.85.46.34]:52626 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750846AbYJaKFt (ORCPT ); Fri, 31 Oct 2008 06:05:49 -0400 Content-Disposition: inline In-Reply-To: <20081026084848.GA9270@infradead.org> Sender: linux-ext4-owner@vger.kernel.org List-ID: Akira, can you please comment on these issues before going on? I think the generation issue is a particularly important one if you want to allow defrag by normal users. On Sun, Oct 26, 2008 at 04:48:48AM -0400, Christoph Hellwig wrote: > On Sun, Oct 26, 2008 at 02:40:48AM -0600, Andreas Dilger wrote: > > This was mentioned last time these patches were posted, but there was > > no reply from you. Christoph suggested a more generic VFS open-by-inum, > > which isn't impossible to do but would cause a lot of controversy I > > think, while the EXT4_IOC_WRAPPER is at least contained within ext4, > > but is more generically useful than EXT4_IOC_FIEMAP_INO. > > I'll hack up a generic open_by_handle and then we can gather the > reaction - it shouldn't be more than about one or two hundred lines of > code. Note that you really want an open by handle and not just inum for > a defragmentation tool - without the generation you can easily run into > races. > > Btw, any reason the XFS approach of passing in *file descriptors* for both > the inode to be defragmented and the "donor" inode doesn't work for you?